Objective-J

Objective-J is basically an implementation of Objective-C language constructs on top of the JavaScript language (Objective-C is the native language used by the Mac OS X application runtime – kind of like .NET for Mac OS).

On top of this language they have basically re-implemented the Cocoa GUI framework as a web-based technology (they call it Cappuccino – they're evidently not tea drinkers). Their flagship application using this system is a web-based slideshow authoring program called 280 slides, which has already been compared favourably to the Macintosh Keynote program (Apple's competitor to Powerpoint).